Optical Articles And Systems Interacting With The Same

ABSTRACT

Optical articles including a spatially defined arrangement of a plurality of data rich retroreflective elements, wherein the plurality of retroreflective elements comprise retroreflective elements having at least two different retroreflective properties and at least two different optical contrasts with respect to a background substrate when observed within an ultraviolet spectrum, a visible spectrum, a near-infrared spectrum, or a combination thereof.

TECHNICAL FIELD

The present disclosure relates to optical articles. More specifically,the present disclosure relates to optical articles that are configuredto be readable and or noticed by both optical systems and humanobservers and systems including such optical articles.

BACKGROUND

Optical systems include methods for acquiring, analyzing, andunderstanding images. Illustrative applications of these systems includerobotics, face recognition, image search, machine vision, remotesensing, surveillance, autonomous vehicles, and object detection to namea few. Some examples of applications of object detection include vehiclevision systems, autonomous vehicles, as well as worker safety.

In recent years, computer vision systems have taken numerous approachesto detecting objects of interest, like pedestrians. Most approaches toobject detection include visible or near infrared cameras. The problemof object detection is complicated due to the complexity and variety ofthe environments in which the optical articles and systems can belocated in (e.g., daytime or nighttime; sunny or cloudy; urban or city;construction, etc.), the variety of the poses that they can take, andthe variety of their appearance based on size, clothing, etc., as wellas due to potential partial occlusion.

Many of the pedestrian detection approaches employ exhaustive scanningover the entire image, or template based silhouette matching, body partmatching. However, due to variety in the forms that humans can take inimages, these approaches are very difficult, time consuming, and haveless than ideal performance.

Similarly, the difficult task of detecting and identifying pedestriansat night by human observers led to introduction and regulation of highvisibility garments. High visibility garments (i.e., garments withretro-reflective materials) are designed to make the wearer more visibleor conspicuous by returning more of the incident light back to the lightsource and in patterns that can be readily recognized by human viewersas other human forms. Current optical systems are based on collecting alarge amount of training data, having human experts annotate it and thentraining a model to detect the specific object of interest. Thiscollection and annotation of data is time consuming and costprohibitive.

Even in view of existing technology related to optical articles, thereremains opportunity for improved optical articles and substrates, suchas infrastructure, wearables, vehicles, and other articles, containingsuch optical articles.

SUMMARY

The present disclosure provides a number of advantages over existingoptical articles and systems used therewith. The present disclosureprovides optical articles that can be readily observed and/or conveyinformation under any conditions to a machine observer, a humanobserver, or both, to allow identification and tracking of such opticalarticles on users or objects.

The present disclosure provides an optical article comprising a datarich plurality of retroreflective elements that are configured in aspatially defined arrangement, wherein the plurality of retroreflectiveelements comprise retroreflective elements having at least two differentretroreflective properties and at least two different optical contrasts,wherein data rich means information that is readily machineinterpretable. In some instances, the data rich plurality ofretroreflective elements are configured in a repeating spatially definedarrangement such that the information is interpretable even when theportion of the retroreflective elements are occluded.

In some instances, the at least two different retroreflective propertiesare at least two different retroreflective intensity values. In someinstances, the at least two different retroreflective properties are atleast two different wavelengths. In some instances, the at least twodifferent retroreflective properties have at least two differentpolarization states. In some instances, the at least two differentretroreflective properties have at least two different phaseretardations.

In some instances, the spatially defined arrangement comprises geometricarrangement in which the retroreflective elements are positioned with adistance from their neighboring retroreflective elements, and whereinthe retroreflective elements have a periodicity from one element toanother within the spatially defined arrangement. In some instances, theperiodicity is a regular periodicity. In some instances, the periodicityis an irregular periodicity. In some instances, the spatially definedarrangement is rotationally insensitive.

In some instances, a number of geometric arrangements are required perspatially defined arrangement depends on a required quality of fit. Insome instances, the retroreflective elements are positioned from theirnearest neighboring retroreflective elements by a characteristicdistance. In some instances, the retroreflective elements have acharacteristic ratio of size to distance to neighboring retroreflectiveelements that is invariant with viewing angle.

The present disclosure provides a fabric comprising the aforementionedarticles.

The present disclosure also includes a system comprising any of theaforementioned articles, an optical system, and an inference engine forinterpreting and classifying the plurality of retroreflective elementswherein the optical system feeds data to the inference engine. In someinstances, the article is disposed on at least one of infrastructure,targets, wearables, and vehicles.

In some instances, the optical system is part of a vehicle, and furtherwherein the vehicle uses the information as an input to an autonomousdriving module. In some instances, the vehicle uses the information toprovide human language feedback to the driver. In some instances, thevehicle uses the information to provide at least one of haptic, audibleor visual feedback to the driver.

In some instances, the data rich plurality of retroreflective elementsis observable or visible in the infrared spectrum with a computer visionsystem, in the visible spectrum with the human eye, or visible withboth. In some instances, the information related to the data richplurality of retroreflective articles comprises at least one of roadworkers expected, pedestrians expected, construction workers expected,students expected, emergency responder workers expected.

In some instances, the inference engine is locally stored as a componentof the optical system. In some instances, the optical systemcommunicates with the inference engine using a wireless communicationprotocol. In some instances the inference engine includes a look uptable with assigned meanings associated with specific patterns of datarich plurality of retroreflective elements. In some instances, theinference engine includes a look up table.

The above summary is not intended to describe each embodiment of thepresent disclosure. The details of one or more embodiments of thepresent disclosure are also set forth in the description below. Otherfeatures, objects, and advantages of the present disclosure will beapparent from the description and from the claims.

BRIEF DESCRIPTION OF DRAWINGS

The invention may be more completely understood in consideration of thefollowing detailed description of various embodiments of the inventionin connection with the accompanying drawings, in which:

FIGS. 1a to 1m show various patterns of retroreflective elementsincluded in the presently disclosed optical articles.

FIGS. 2a and 2b show the presently disclosed optical articles disposedon an objects.

FIG. 3 shows a rendered image of an environment including the shape inpresence of distractors produced by a software and an automaticextraction of the regions of interest (ROI) for the shapes from thesynthetically generated image according to some embodiments of thepresently disclosed system.

FIG. 4 depicts a flowchart describing the steps for evaluating thesaliency of an input shape using synthetically generated data accordingto some embodiments of the presently disclosed system.

FIG. 5 depicts an image of the object of interest (carrier pattern). Theimages are annotated with a bounding box located around the object asshown in (a). A machine learning model is trained to disambiguatebetween this carrier pattern and other objects found in the environmentin (b).

FIG. 6 depicts an exemplary modifications to a carrier pattern. Thecarrier pattern is shown in (a). A modification to the pattern caninclude a gap introduced into the middle of the strips as shown in (b)or repeating gaps in the form of a segmented trim like that shown in(c).

FIG. 7 depicts images of instances of different sub-categories of thecarrier pattern.

FIGS. 8a and 8b depict an exemplary system for image processing usefulin some embodiments in the presently disclosed system.

FIG. 9 shows an overview of an evaluation process of possible shapearrangements useful in algorithms that can be used in some embodimentsof the presently disclosed system.

FIG. 10 shows a design with a fit (or saliency) score of 0.752332,produced after 1484 generations of the genetic algorithm useful in someembodiments in the presently disclosed system.

FIG. 11 shows the design from FIG. 10, rendered onto 3D vest model by analgorithm useful in some embodiments in the presently disclosed system.

FIG. 12 shows an exemplary function that can be used for optimizingdesigns in the presently disclosed system.

FIG. 13 depicts an exemplary genetic algorithm useful in someembodiments in the presently disclosed system.

FIG. 14 depicts an embodiment for a workflow for a single image instanceuseful in some embodiments in the presently disclosed system.

FIG. 15 depicts an embodiment for a workflow for an input image usefulin some embodiments in the presently disclosed system.

FIG. 16 a process scheme for training and testing a system for observingdisclosed articles.

FIGS. 17a, 17b and 17c show images of three articles demonstrated inExample 1.

FIGS. 18a, 18b, 18c and 18d show images of four different articlesdemonstrated in Example 2.

FIGS. 19 to 33 illustrate illustrative patterns of retroreflectiveelements demonstrated in Example 5.

FIG. 34 is an image of panels oriented close to ‘head-on’ entrance angleorientation for modified ‘yaw angle’ experiment. Distance from panel tosource/camera was approximately 152 m.

FIG. 35 is a magnified image of the test panel from FIG. 34 identifyingthe 0.025×0.025 m retroreflective elements.

FIG. 36 is an image of the test panel oriented at a ‘yaw angle’orientation of approximately 30 degrees with respect to the viewingdirection.

FIG. 37 is a magnified image of the test panel from FIG. 36 identifyingthe 0.025×0.025 m retroreflective elements.

FIG. 38 is an image of the vests of Example 3a and CE3e taken in thedark with a near infrared system.

It is to be understood that the embodiments may be utilized andstructural changes may be made without departing from the scope of theinvention. The figures are not necessarily to scale. Like numbers usedin the figures refer to like components. However, it will be understoodthat the use of a number to refer to a component in a given figure isnot intended to limit the component in another figure labeled with thesame number.

DETAILED DESCRIPTION

Optical articles, such as retroreflective articles, redirect lightincident on the article back toward its source. This property has led tomany practical applications of retroreflective articles in the areas oftraffic and personal safety. Retroreflective articles are currently usedfor traffic signs, car license plates, pavement markings, constructionzone cones and barrels, and high visibility material on clothing worn byusers (e.g., workers, pedestrians, animals, etc.).

Systems that interact with optical articles such as retroreflectivearticles include observers such as computer vision systems, opticalsystems and human observers. Disclosed retroreflective articles arevisible by one or more of these observers in various types and levels ofenvironmental conditions both initially and even after extended use.

The plurality of retroreflective elements includes retroreflectiveelements, where these plurality of retroreflective elements have atleast two different retroreflective properties and at least twodifferent optical contrasts with respect to a background substrate whenobserved within the ultraviolet spectrum, the visible spectrum, thenear-infrared spectrum, or any combination thereof.

One of the biggest challenges to the performance of retroreflectivearticles is the vast and varied environmental factors that can affectthe performance thereof. For example, retroreflective articles aredesired to work in full light conditions (daytime full sun for example),full dark conditions (nighttime cloudy conditions for example), andeverything in between. The specific factors that can play a role in howa particular retroreflective material or combination thereof mayfunction can include, for example, brightness or lack thereof of thesun; angle and/or location of the sun with respect to the article; angleand/or location of the sun with respect to the observer; presence,absence or a combination thereof of clouds; presence, absence or acombination thereof of shadows; angle and/or location of shadows withrespect to the article; angle and/or location of shadows with respect tothe observer; angle and/or location of shadows with respect to thearticle; presence, absence or combination thereof of light sources otherthan the sun; angle and/or location of light sources other than the sunwith respect to the article; angle and/or location of light sourcesother than the sun with respect to the observer; presence or absence aswell as intensity of moisture level on article; and presence or absenceof fog.

Different types of retroreflective articles can have differentretroreflective responses to various environmental factors; differenttypes of retroreflective articles can have different optical contrastresponses with respect to the background thereof, to variousenvironmental factors; and some retroreflective articles can have both adifferent retroreflective response and an optical contrast response withrespect to the background thereof, to various environmental factors. Inan illustrative scenario, two environmental factors that can have themost negative affect on observed optical contrast may include the angleof the sun with respect to the article, the observer, or both and thepresence of dark shadows. For example, when the sun is behind theobserver but falling directly on the object to be viewed, the directsunlight on the garment containing the retroreflective article cansaturate the sensor (either the eye of a human observer or a sensor of anon-human observer) such that there is no observable contrast betweenthe retroreflective article and the background thereof for certaincombinations of retroreflective articles and backgrounds. Similarly,when the sun is behind the object with the retroreflective article, theshadow cast on the observable side might be so dark that once again,there is no detectable contrast between the retroreflective article andthe background thereof for certain combinations of retroreflectivearticles and backgrounds. Combinations of retroreflective articles andbackgrounds that provide additional optical contrast when compared toother combinations under such conditions may therefore be moreadvantageous by providing more robust detection across more lightingconditions.

It is advantageous that a retroreflective article can functionsufficiently well in all lighting conditions, for example, because it isnot practical for a user of a retroreflective article containing garmentto stop and change the particular retroreflective article containinggarment when the sun goes under a cloud or moves across the sky, forexample.

Optical Contrast Difference

Disclosed optical articles include at least two and in most embodimentsa plurality, e.g., more than two, retroreflective elements. Theretroreflective elements have at least two different optical contrastswith respect to a background substrate when observed within theultraviolet spectrum, the visible spectrum, the near-infrared spectrum,or any combination thereof.

The term “ultraviolet” refers to energy having a wavelength in the rangefrom 10 nanometers (nm) to 400 nm. The term “ultraviolet spectrum”refers to the wavelength range from 10 nm to 400 nm.

The term “visible” refers to energy having a wavelength typicallyvisible by the naked human eye and in some embodiments refers to energyhaving a wavelength in the range from 400 nm to 700 nm. The term“visible spectrum” refers to the wavelength range from 400 nm to 700 nm.

The term “near infrared” refers to energy having a wavelength in therange from 700 nm to 2500 nm. The term “near infrared spectrum” refersto the wavelength range from 700 nm to 2500 nm.

In some embodiments, two different optical contrasts with respect to abackground substrate when observed, within the ultraviolet spectrum, thevisible spectrum, the near-infrared spectrum, or any combinationthereof, can be determined by a measurement technique, observation, or acombination thereof.

In some embodiments, two different optical contrasts with respect to abackground substrate, when observed using the human eye, can bedetermined by viewing the two different retroreflective elements. Insome embodiments, two different optical contrasts with respect to abackground substrate when observed using a detector or imager can bedetermined by measuring the optical contrast or at least some componentthereof.

In some embodiments, one method of measuring the optical contrastincludes the use of a colorimeter. A colorimeter can determine the“color” of both retroreflective elements and it can then be determinedif they are different. This can be done using the original colors of thetwo retroreflective elements or by converting the two retroreflectiveelements into grayscale and determining if the two colors are different.Such a method can be useful but in some situations can suffer fromdifferences in the number of pixels in a sensor for example. As thenumber of pixels decreases, the ability to distinguish two differentoptical contrasts decreases. In embodiments, utilizing a colorimeter,different optical contrast values can be determined by the hardware thatis being utilized to measure the optical contrast.

In some embodiments, one method of measuring the optical contrastincludes the use of measuring brightness. This method could be usefulfor retroreflective articles that are meant or particularly advantageousfor nighttime only use, as the difference in the brightness could be anoverwhelming contributor to the difference in optical contrast. In someembodiments, the luminous flux of the two retroreflective elements canbe measured to determine if the optical contrast is different. Inembodiments, utilizing luminous flux, different optical contrast valuescan be determined by the hardware that is being utilized to measure theluminous flux.

In some embodiments, a difference in optical contrast which may beprimarily due to brightness can also be determined by a human observeras two different levels of brightness. One relationship between themagnitude of a physical stimulus, of which brightness is an example, andits perceived intensity or strength is given by Steven's power law. Thegeneral formula of the law is Ψ(I)=kI^(α), where I is the magnitude ofthe physical stimulus, Ψ(I) is the subjective magnitude of the sensationevoked by the stimulus, α, is an exponent that depends on the type ofstimulation, and k is a proportionality constant that depends on theunits used. The exponent, α basically indicates how much brightersomething has to be for an average human observer to perceive that it isbrighter, e.g., that it has a different optical contrast. In someembodiments, a brightness difference of 0.33 times can be perceived by ahuman observer as brighter when the stimulus condition is a 5° target inthe dark; in some embodiments a brightness difference of 0.5 times canbe perceived by a human observers as brighter when the stimuluscondition is a point source; in some embodiments, a brightnessdifference of 0.5 times can be perceived by a human observer as brighterwhen the stimulus condition is a brief flash; and in some embodiments, abrightness difference of 1 time can be perceived by a human observer asbrighter when the stimulus condition is a point source briefly flashed.

In some embodiments, one method of measuring the optical contrastincludes the use of the Bidirectional Reflectance Distribution Function(BRDF). The BRDF provides the reflectance of a target as a function ofillumination geometry and viewing geometry. The BRDF depends onwavelength and is determined by the structural and optical properties ofthe surface, including for example shadow-casting, multiple scattering,mutual shadowing, transmission, reflection, absorption, and emission bysurface elements, facet orientation distribution, facet density, andcombinations thereof. The BRDF simply describes, albeit in a complexmanner, what is observed by the human eye.

Quantifying the visual contrast between a retroreflective material andthe background material thereof under real-world conditions can besomewhat complex. A typical method could include measuring the color ofthe retroreflective materials (as discussed above). The color ofmaterials is often defined as a simple measurement consisting of metricsthat defined a combination of luminance or intensity and chromaticity.An example of such a measurement is CIE 1931 Yxy color space, in which Ycorresponds to the luminance, with x and y as chromaticity coordinatesdefining a specific hue on a chromaticity chart. The color is typicallydefined for a particular illumination source corresponding to thespecific lighting environment (e.g. D65 and F2 used to replicatedaylight and a specific fluorescent spectral illumination,respectively). The color can be measured using a colorimeter in whichthe color is measured under a well-defined orientation for source andreflected light.

However, standard color measurements may not provide a good predictorfor whether a retroreflective material would provide good visualcontrast in outdoor viewing conditions. The visual contrast between tworeflecting opaque objects under different daylight illuminationconditions and orientations is typically more complex than a simplecomparison of color parameters from a colorimeter. The reflectedluminance of the retroreflective material may be the most importantfactor. However, the degree to which light is reflected depends on thelocal orientation of the viewer (or detector, in the case of machinevision) and the position of light relative to the surface normal of thematerials under illumination. As the orientation of either theillumination, the observer or the reflected material changes, thereflected luminance will change. In addition, the presence of curvatureon a garment including natural drape around a human form, as well as thepresence of folds, wear, or combinations thereof can create highlynon-uniform local reflection geometries with respect to either a humanobserver or a camera associated with a machine vision.

Bidirectional reflectance distribution function (BRDF) measurements canbe made to quantify the angular distribution of the reflected luminancefrom a sample for several incidence angles to explore reflective opticalcontrast under a variety of observed conditions. Such measurements canbe referred to as Bright Coverage Determination. For photometry, theBRDF is defined as the reflected luminance divided by the incidentilluminance and will be referred to as the photopic BRDF. BRDFs have theunits of inverse projected solid angle, which is inverse steradian. EachBRDF data point is associated with an incident light direction and ascattered light direction. The scattered directions are specified usingthe projected angle space which is a circular region with radius 1 inthe x-y plane. The z direction corresponds to the direction normal tothe sample. Integrating a BRDF over the entire scattered angle spaceprovides the total reflectance (TR). For an arbitrary point in theprojected angle space, the distance from the origin is equal to the sineof the inclination angle (angle between the z-axis and the direction ofscatter) and the azimuthal angle of the point relative to the x-axisgives the azimuthal direction of the scattered light relative to thex-axis. The advantage of using the projected angle space is that thearea of a region in the projected angle space is equal to the projectedsolid angle. Multiplying the projected solid angle by the average BRDFin the projected solid angle gives the fraction of the incident lightthat is reflected into this angular region. The projected angle spacehave coordinates of u_(X) and u_(Y), where

u _(X) =u*sin(ϕ) u _(Y) =u*cos(ϕ) u=sin(θ)

θ (theta) is the inclination angle and ϕ (phi) is the azimuthal angle.The projected angle space will be referred to as u_(X)-u_(Y) space.

The photopic BRDF can be and were measured for fixed incidence angles.By thresholding the photopic BRDF with a predetermined cutoff value in aspecified region in u_(X)-u_(Y) space (u<)sin(70°) and u_(Y)<θ−15°), thepercentage of the specified region that is above the threshold can becalculated and can be referred to as the “bright coverage”.

In some embodiments, a retroreflective material can be distinguishedfrom a background when the photopic BRDF is below about 0.1±0.05 inversesteradian over a sufficiently large region in the u_(X)-u_(Y) space. Thesurface normal direction of the retroreflective material can vary aboutthe body and with the time of day resulting in the sampling of a largeregion of the u_(X)-u_(Y) space. If the bright coverage is high, thenunder sunlight, a larger fraction of the retroreflective material wouldbe bright (higher luminance) and more difficult to distinguish from thebright garment material.

In some embodiments, a difference in optical contrast of two differentretroreflective elements can be described by a BRDF cutoff value that isutilized to calculate a bright coverage. For example, a 0.05 brightcoverage defines a bright coverage calculated using a BRDF cutoff valueof 0.05 steradian. In some embodiments, two retroreflective elementshave a different optical contrast when they have a 0.05 bright coveragewith a weighted average of less than 50 percent; when they have a 0.05bright coverage with a weighted average of less than 25 percent; whenthey have a 0.05 bright coverage with a weighted average of less than 15percent; when they have a 0.10 bright coverage with a weighted averageof less than 50 percent; when they have a 0.10 bright coverage with aweighted average of less than 25 percent; when they have a 0.10 brightcoverage with a weighted average of less than 15 percent; or when theyhave a 0.15 bright coverage with a weighted average of less than 15percent.

In some embodiments, the retroreflective properties can have at leasttwo different colors as well. In some embodiments, at least some of theretroreflective elements are black and at least some of theretroreflective elements are silver. In some embodiments, at least someof the retroreflective elements are black and at least some of theretroreflective elements are silver and the background or a substrateupon which the plurality of retroreflective elements are located isfluorescent. In some embodiments, at least some of the retroreflectiveelements are black and at least some of the retroreflective elements aresilver and the background or a substrate upon which the plurality ofretroreflective elements are located is fluorescent orange orfluorescent lime-yellow.

Retroreflective Properties

The retroreflective elements have at least two different retroreflectiveproperties. The term “retroreflective” refers to the phenomenon ofenergy (e.g., light rays) striking a surface and being redirected backtowards the source of energy. The retroreflective nature of an elementcan be caused by illumination with any source of energy. In someembodiments, the retroreflective nature of an element can be caused by anatural source (e.g., the sun, the moon, etc.); or a non-natural source(e.g., headlights, streetlights, etc.).

The plurality of retroreflective elements include elements having atleast two different retroreflective properties. In some instances, theat least two different retroreflective properties are at least twodifferent retroreflective intensity values. In some instances, the atleast two different retroreflective properties are at least twodifferent wavelengths of reflection. In some instances, the at least twodifferent retroreflective properties have at least two differentpolarization states. In some instances, the at least two differentretroreflective properties at least two different phase retardations. Insome embodiments, the at least two different retroreflective propertiesare at least two different retroreflective intensity values, at leasttwo different wavelengths of reflection, at least two differentpolarization states, at least two different phase retardations, or somecombination thereof.

Observed in Ultraviolet Spectrum, Visible Spectrum, Near-InfraredSpectrum or Both

In some embodiments, the optical articles, the optical contrast thereof,or some combination thereof can be observed by a system capable ofobservation thereof in the ultraviolet spectrum. In some embodiments,the optical articles, the optical contrast thereof, or some combinationthereof can be observed by a system capable of observation thereof inthe visible spectrum In some embodiments, the optical articles, theoptical contrast thereof, or some combination thereof can be observed bya system capable of observation thereof in the near-infrared spectrum.In some embodiments, the optical articles, the optical contrast thereof,or some combination thereof can be observed by a system capable ofobservation thereof in some combination of the ultraviolet spectrum, thevisible spectrum, and the near-infrared spectrum. In some embodiments,the optical articles, the optical contrast thereof, or some combinationthereof can be observed by a system capable of observation thereof insome combination of the visible spectrum and the near-infrared spectrum,the visible spectrum, or the near-infrared spectrum.

Being observed herein can include being perceived, visualized, viewed,imaged, detected, monitored, or any combination thereof. The observationcan be undertaken by a human observer; a machine or computer observer,imager, detector, visualizer, or a combination thereof; or by acombination of a human and a machine.

Machine observers can include at least a camera. An example of an RGBcamera system includes, for example, a FLIR Machine Vision (formerlyPoint Grey) CHAMELEON®3 5MP Color Camera (CM3-U3-50S5C-CS) (FLIRIntegrated Imaging Solutions Inc., Richmond BC, CANADA). The camerasystem may be modified with lens' of varying focal length, including,for example an Edmund Optics 25 mm C Series Fixed Focal Length Lens(Edmund Optics Inc. Barrington, N.J.). Illustrative light sources forRGB camera systems may be either ambient illumination or automobileheadlights. An example of an NIR camera system includes, for example, aFLIR Machine Vision (formerly Point Grey) CHAMELEON®3 5MP Color Camera(CM3-U3-50S5C-CS) (FLIR Integrated Imaging Solutions Inc., Richmond BC,CANADA). The NIR camera system may be modified with lens' of varyingfocal length and/or filter, including, for example, an Edmund Optics 25mm C Series Fixed Focal Length Lens (Edmund Optics Inc. Barrington,N.J.), a BN940 Narrow Near-IR Bandpass Filter (BN940-25.5) (MidwestOptical Systems, Inc. Palatine, Ill.), or combinations thereof.Illustrative light sources for NIR camera systems may include a 130 mmOver Drive Ring Light 940 nm IR—“EZ Mount Ring Light” from Smart VisionLights (Muskegon, Mich.).

Disclosed retroreflective articles can be advantageous because they canoffer observation to both human and machine observers in a number ofdifferent environmental conditions, whether or not a portion of theretroreflective article is occluded.

Angular Sensitivities

In some embodiments, the plurality of retroreflective elements can haveat least two different angular sensitivities as well. The differentangular sensitivities results from the retroreflective property of theretroreflective material. Various combinations of retroreflectiveelements can be utilized to create a pulsing effect, not create apulsing effect, or a combination thereof; a flickering effect, notcreate a flickering effect, or a combination thereof; or a combinationthereof. A pulsing effect is caused in part by overglow, as oneretroreflective element ceases to reflect, the overglow of the brighterretroreflective element (at that particular angle) appears to getbrighter, e.g., pulse. As the angle of the incident light changes(either by the article moving or the light source moving, or both), oneor more of the retroreflective elements will have a change inretroreflectiveness. In some embodiments, the plurality ofretroreflective elements can produce a pulsing effect when illuminatedwith a source of energy. The pulsing can be advantageous because it candistinguish one object from another, an object from a human, or twoother types of objects.

Different angular sensitivities can be combined with different shapes,different sizes, different patterns, or any combinations thereof tocreate different types of effects, including for example pulsing,blinking, a strobe light effect, a flickering, etc. Because of thedifferent off-angle retro-reflective properties of the materials,different angles can create different appearances of the overallarticle. For example, at head on angles, where all materials reflectwell, the full array is seen while at angles further to the side fromhead on (off angles) materials with low off-angle retro reflectivity donot reflect much therefore such retroreflective elements appear todisappear at off angles. Different patterns, such as checkerboard,bullseye and columnar patterns were investigated and can providedifferent effects, such as those seen below in the examples.

Different angular sensitivities of at least two retroreflective elementscan also be utilized when observed (by a machine observer, a humanobserver, or both) to infer the location, angle, etc. of the observerwith respect to a fixed object. For example, different angularsensitivities can be used to determine the distance an observer is froman object because the angular sensitives are distance dependent, in thatthe effect (e.g., flickering, pulsing, etc.) occurs only within adistance range from the retroreflective element.

Spatially Defined Arrangement

The present disclosure provides an optical article comprising a datarich plurality of retroreflective elements that are configured in aspatially defined arrangement.

The term “data rich” as used herein means information that is readilymachine interpretable.

At least some of the retroreflective elements are discontinuous. In someembodiments all of the plurality of retroreflective elements arediscontinuous. By discontinuous, it is meant that the edges of theretroreflective elements do not contact each other and theretroreflective elements do not overlap.

In some embodiments, the data rich plurality of retroreflective elementsare configured in a repeating spatially defined arrangement such thatthe information is interpretable even when the portion of theretroreflective elements are occluded. In some embodiments, at leastsome of the plurality of retroreflective elements are discontinuous. Insome embodiments, most of the plurality of retroreflective elements arediscontinuous. In some embodiments, all of the plurality ofretroreflective elements are discontinuous.

FIG. 1a illustrates the effect of occlusion and pattern replication. Theupper-left quadrant shows a sample base pattern of retroreflectiveelements. In this example, imaging that the pattern is identifiable ifboth of the circles are visible; the upper-right quadrant shows the samebase pattern with one replication; in the lower-left quadrant of FIG. 1aa white object has occluded one of the elements in the pattern. In thiscase, the occlusion results in an inability to detect the pattern. Inthe lower-right quadrant once again a white object is occluding one ofthe elements of the pattern but due to the replication there are stillsufficient elements for detection of pattern of the optical article by asystem, such as a visions detection system. Various patterns ofretroreflective elements can be used in the present disclosure, such asthe exemplary designs shown in FIGS. 1b to 1 m.

In some embodiments, a particular spatially defined arrangement can beutilized to classify the entity (e.g., user or object) that theretroreflective article exists upon. If the classifier in a system, suchas a vision detection system, is based on checking the number ofretroreflective elements in the pattern against a minimum requirednumber of retroreflective elements, a pattern containing at least onemore element than the specified minimum will be detectable under partialocclusion. In comparison, a classifier in a system, such a visiondetection system, looking for a specific number of retroreflectiveelements is not robust when at least one of the retroreflective elementsin the pattern is occluded.

The present disclosure also provides that the plurality ofretroreflective elements can have the same or different shapes. Usefulshapes for individual retroreflective elements includes, but are notlimited to, circles, stars, squares, polygons, curved and irregularshapes, and the like. These individual retroreflective elements can bearranged in a mathematical way of arranging shapes such that thearrangement can be detected independent of the individual componentshapes, optionally the individual component shapes could add additionalinformation. Mathematical arrangement refers to a scheme for sizing andspacing apart the components of the resulting optical article.

These retroreflective elements or resulting optical articles may beeither standalone or may be repeating to increase robustness to partialocclusion. If the elements or articles are small, repetition may berequired for robust detection, if the optical article is large it islikely to be robust to partial occlusion due to a subset being visible.

Optionally any number of the component shapes could be engineered toselectively reflect light of different wavelengths and/or polarization.For example, in some embodiments, retroreflective elements withproperties sufficient to meet regulatory standards (e.g., ANSI/ISEA107-2015′ compliant material) but a subset of the optical article isconstructed such that it has special optical properties (e.g.,wavelengths and/or polarization reflected) such that a system (such as acomputer vision system) can discriminate between these sections of theoptical article and the rest of the optical article or objects on whichit is mounted. One example of the utility of such a construction mightbe, if to be regulatory compliant gaps in the retroreflective elementshad to be less than X mm, but computer vision system detectionnecessitated gaps greater than X mm. These two requirements would be inconflict unless the construction of the retroreflective elements allowedthe computer vision system to only see a subset of the retroreflectiveelements but the entire (or at least a portion of the optical article orretroreflective elements) is sufficient to meet standards because theresulting optical article is reflective to light in a spectrum that isdetectable by humans.

In some embodiments, the number of unique retroreflective elements inthe optical article, should be robust to deformation and perspectivechanges up to the point where retroreflective elements become completelyoccluded or they begin to merge together versus density of brightpixels.

The spacing and feature size of the retroreflective elements (or shapes)comprising the optical article will likely need to factor in over-glow.One optional construction of the present disclosure might includeretroreflective elements that are constructed of more than one level ofreflective material so as to reduce effect of over-glow. For example,the outer edge of the retroreflective elements might be constructed fromlower R_(A) material as compared to the internal portion of theretroreflective elements. In some embodiments, a minimum measureddifference in R_(A), such as at least a difference of 5%, 10%, 20%, 50%or more, is useful.

The retroreflective elements can be manufactured by any number ofmethods including but not limited to: screen printing, weaving,stitching, and the like. In some embodiments, the optical article is adeformable optical article. In some instances, the deformation is causedby shrinkage, expansion, or both. In some instances, the deformationcauses a spacing change between at least two of the retroreflectiveelements. In some instances, the deformation is reversible.

In some instances, the aforementioned retroreflective property changesin response to a change in condition. For example, a change in conditionthat could cause a change in at least one of the retroreflectiveproperties of the plurality of retroreflective elements could be achange in thermal, moisture, mechanical deformation, or radiation.Thermal changes could be changes in ambient temperature, for example.Exemplary moisture changes include changes in ambient humidity or thepresence of precipitation in an environment in which the optical articleis being used. Mechanical deformation could include, for example,wrinkling of a garment on which the optical article is mounted.

In some instances, the retroreflective elements are individually sizedand separated from one another such that each individual retroreflectiveelement is resolvable at desired distances from the optical article.

In some instances, the spatially defined arrangement comprises geometricarrangement in which the retroreflective elements are positioned with adistance from their neighboring retroreflective elements, and whereinthe retroreflective elements have a periodicity from one element toanother within the spatially defined arrangement. In some instances, theperiodicity is a regular periodicity. In some instances, the periodicityis an irregular periodicity. In some instances, the spatially definedarrangement is rotationally insensitive.

In some instances, a number of geometric arrangements are required perspatially defined arrangement depends on a required quality of fit. Insome instances, the retroreflective elements are positioned from theirnearest neighboring retroreflective elements by a characteristicdistance. In some instances, the retroreflective elements have acharacteristic ratio of size to distance to neighboring retroreflectiveelements that is invariant with viewing angle.

In some instances, the optical article further comprises a printed layerdisposed on the outer surface of at least a portion of theretroreflective elements. In some instances, the retroreflectiveproperties are detectable in the infrared spectrum.

In some instances, the optical article is disposed on a substrateselected from at least one of objects, infrastructure, wearables, andvehicles. The present disclosure provides a fabric comprising theaforementioned articles.

System Including Retroreflective Article

The present disclosure also includes a system comprising any of theaforementioned articles, an optical system, and an inference engine forinterpreting and classifying the plurality of retroreflective elementswherein the optical system feeds data to the inference engine. In someinstances, the article is disposed on at least one of objects,infrastructure, targets, wearables, and vehicles.

In some instances, the optical system is part of a vehicle, and furtherwherein the vehicle uses the information as an input to an autonomousdriving module. In some instances, the vehicle uses the information toprovide human language feedback to the driver. In some instances, thevehicle uses the information to provide at least one of haptic, audibleor visual feedback to the driver.

In some instances, the data rich plurality of retroreflective elementsis visible in the infrared spectrum to a computer vision system. In someinstances, the information related to the data rich plurality ofretroreflective articles comprises at least one of road workersexpected, pedestrians expected, construction workers expected, studentsexpected, emergency responder workers expected.

In some instances, the inference engine is locally stored as a componentof the optical system. In some instances, the optical systemcommunicates with the inference engine using a wireless communicationprotocol. In some embodiments, the inference engine and the opticalsystem can include various features and steps as disclosed in thefollowing section on methods and systems useful in the presentdisclosure.

The presently disclosed system is useful for various applications. Forexample, the presently disclosed system utilizes the presently disclosedoptical article for the purpose of simplifying and enhancing detectioncapabilities of a system, such as a computer vision pedestriandetection, which allows for the system to determine location,identification, and/or pose of an individual wearing a garment,accessory or other objects on which the optical article is disposed. Thedata rich content in the plurality of retroreflective elements aids insimplification of the task of pedestrian detection by reducing thenumber of distractors that the optical system needs to evaluate by firstthresholding the image based on properties of the optical (such as, forexample, intensity and/or color spectrum of the light returned) and thenevaluating those segmented regions for meaningful shapes (or patterns)based on the design of the garment, accessory or other article on whichthe optical article is disposed and likely poses of the wearer.

The presently disclosed system includes at least one camera, a lightsource (such as, for example, vehicle headlights, or other visible, NIR,or FIR light sources), and the presently disclosed optical articles. Thepresently disclosed system utilizes the pattern of light returned fromthe optical article to identify the object on which the optical articleis disposed, infer pose, position, likelihood of intersection, etc. Onepossible embodiment might utilize a garment design, such as thoseillustrated in FIGS. 2a and 2b . In this example, a frontal view of thegarment has a different number and pattern of visible optical articleshaving a plurality of retroreflective elements than a profile view ofthe garment. If the optical articles on the garment are of a known size(for example, if the chevrons in this case are all 6 inches in length)then the system could infer relative distance and position of the wearerfrom the camera based on projected size and position.

The present disclosure includes a system and method for automaticallyevaluating the saliency of design shapes, such as optical articles and aplurality of retroreflective elements included therein, for anapplication environment without having to collect real world data(images/videos) of such shapes.

The sequence of steps to perform this methodology is depicted in FIGS.3a and 3b ; and described here:

The input to the system is the shape of interest, such as opticalarticles and a plurality of retroreflective elements included therein.For the application environment, a set of distractor shapes (or objects)which commonly occur in the environment is known e.g. for a highwayapplication, the distractor set can include highway information sign,speed limit sign, cones, barrels, and the like.

The design shape (such as optical articles and a plurality ofretroreflective elements included therein) placed on an object ofinterest (such as infrastructure, garments, accessories, and the like)and distractor set is input into an algorithm or software for generatinga synthetic dataset of images and videos. This includes, but is notlimited to, a render software which uses a 3D model of the environmentto produce a rendering of the object in that environment. This willgenerate data which can simulate effects like lighting effects,viewpoint variations, environment clutter, object motion, and the like.FIG. 3a shows a sample rendered image of a highway worker wearing a highvisibility garment with an exemplary optical article of the presentdisclosure as the design shape in the frontal portion of his garment.

The regions of interest (ROI) corresponding to the design shape (e.g.,optical articles and a plurality of retroreflective elements includedtherein) and the distractor are extracted from the images. FIG. 3b showsone such example of ROIs extracted from a rendered image. This processcan be automated using knowledge about the 3D model provided for therendering of the environment.

For each extracted ROI, features characterizing their properties likeappearance, shape, texture, geometry are computed e.g. shape context,histogram of oriented gradients, area, etc.

The computed features can then be input into an algorithm, an example ofwhich is shown in FIG. 4, that can generate the saliency score for thedesign shape (e.g., optical articles and a plurality of retroreflectiveelements included therein) against the set of distractor shapes. Thesaliency evaluation generates a quantitative score for the designshape's uniqueness amongst the set of distractors.

The present disclosure also provides a system and method that modifiesretroreflective shapes (such as optical articles and a plurality ofretroreflective elements included therein) on objects of interest (suchas infrastructure, garments, accessories, and the like) to provideadditional information. In this invention, the object of interest isalso referred to as a carrier pattern. Exemplary objects of interest, orcarrier patterns, include a high-visibility safety vest worn by workersin work-zones, barrels used in roadside construction zones to marknavigation limits, and other infrastructure, garments, accessories, andthe like. The sequence of steps to perform this methodology is describedhere:

Annotated images of the carrier pattern are collected for theenvironment. These include the images of objects from varying distances,poses and viewpoints. As an example, FIG. 5 includes examples ofretroreflective vests worn by individual workers in workzones.

A machine learning model can be trained to classify image patches as thecarrier pattern or not. To train this model, image patches of thecarrier pattern and the background (image patches which do not includethe carrier pattern) are provided. Image features characterizing theappearance of these image patches like a histogram of oriented gradients(HOG) or shape context are computed. These features are then used totrain a classifier model e.g. Support Vector Machine (SVM) or DecisionTrees. The input to this model is the computed feature for an imagepatch and the output can be (but not limited to) yes/no answer forpresence of the carrier pattern in the input image patch.

Given a carrier pattern and based on the requirements of the system forthe environment, modifications are made to the retroreflective shape ofthe carrier pattern. An example is provided in FIGS. 6a, 6b and 6c wherethe H-shape used in safety vests is partially modified to produce twoadditional sub-categories of the pattern. The modifications are not justlimited to size and could include changes to the color of the patternalso.

Images of the different sub-categories are collected in a datacollection experiment or through a synthetic data generation module.Besides collecting images of the different sub-categories individually,it is also possible that the carrier pattern image already includeinstances of the sub-category and a clustering algorithm can be used todiscover these instances

A sub-categorization classifier is trained using instances of thedifferent subcategories as shown in FIG. 7.

At runtime, the system first looks for the presence of the carrierpattern. Having detected the carrier pattern in an image patch, thatimage patch is then processed by the subcategorization module for thesub-category present in the image. Examples are provided in FIG. 8a andFIG. 8 b.

In some embodiments, the presently disclosed system also provides orincludes two algorithms that are used to 1) initialize the boundary of ashape of an optical article that is placed on an object of interest,such as a garment and 2) define an objective function that measures theusefulness or fit of that boundary configuration. Each of the algorithmssearches the space of possible geometries and yields a geometry thatoptimizes that objective function.

FIG. 9 illustrates the process of evaluating each possible geometry(parameterized as a set of [x, y] points). In some embodiments, one ofthe algorithms is a genetic algorithm and the other algorithm is anumerical gradient-based optimization algorithm. Each of thesealgorithms uses a different technique to generate sample geometries,evaluate them, and attempt to further generate new arrangements withimproved evaluation scores.

In some embodiments, the plurality of retroreflective elements areplaced in configurations that produce designs, such as garment designs,which are highly salient to a system, such as systems used by motorists(see FIG. 10). The term “highly salient” as used herein means somethingthat stands out from other entities or features in an environment. Theobjective function assesses the saliency of a design by applying thatdesign as a texture to a 3D model of a vest (e.g., the kind of vest wornby a construction worker). A 3D Modeling application (e.g., Blender) isused to produce several different views of this 3D model (see FIG. 11).The resulting views are fed into a clustering algorithm, as well as aset of ‘distractor’ shapes. The distractor shapes depend on anapplication space. In some embodiments, distractor shapes are objectsthat can be confused as the object of interest in the presentlydisclosed systems and methods. The clustering algorithm groups theseinputs into clusters.

In some embodiments, clustering accurately sorts each of these designsinto one cluster and each of the distractor shapes into the othercluster. This results in a fitness of 1.0. Fit can be quantified by‘Silhouette Score’, which measures the quality of a set of clusters,based on known ground truth labels. In other words, Silhouette Score isused to measure how well the clustering algorithm performs. There areother potentially useful methods of quantifying the quality of a set ofclusters.

In some embodiments, a SciPy optimization toolkit for Python can be usedto produce a design as a part of our proof-of-concept experiment, wherean objective function that generated circular shapes is used. The SciPyfunction is called scipy.optimize.minimize. This function is suppliedwith 1) a list of [x, y] points that define the starting configurationof the boundary of the polygonal shape of the design (such as an opticalarticle using a plurality of retroreflective elements), 2) an objectivefunction that quantifies the cost of a particular configuration of thisdesign, with lower values being better 3) a specification of whichoptimization method to use for the optimization, and 4) a list of shapeor size constraints.

In some embodiments, the Optimization Method is chosen from a list ofoptions in the documentation (e.g. Sequential Least SquaresProgramming). The Constraints might be defined to constrain any or allof the constraints listed in FIG. 12. A genetic algorithm can be used todetermine a possible data structure. The data structure can be called achromosome (with an analogy to the container of genetic material in aliving system).

The genetic algorithm generates multiple chromosomes (either completelyrandomly or by making random variations on a seed design). The fitnessof each chromosome is then determined. The chromosomes with poor fitnessare deleted and replaced with copies of the highly fit chromosomes. Thenew copies are modified using mutation operators. A mutation operatorapplies stochastic changes to some of the values in the chromosome. Thecopies may be produced using an operation called crossover, whereby eachchild gets genetic material from multiple parents, though crossover isnot always required.

In some embodiments, the chromosome is a list of points. Each pointdefines the vertex of a shape comprising the optical article having aplurality of retroreflective elements. The genetic algorithm favorsgeometries with high fitness (e.g., in this case, with fitness that ismost nearly equal to 1.0). Geometries with high fitness tend to stay inthe population, and geometries with low fitness tend to be excluded fromthe population due to the selection operation.

FIG. 13 describes the genetic algorithm (GA). The population ofchromosomes can be initialized randomly or initialized using pre-evolvedchromosomes. The population may alternatively be initialized using thetop N most-fit chromosomes from a set of thousands of randomly generatedchromosomes. Similarly to the numerical optimization algorithm, thegenetic algorithm uses the saliency objective function. The objectionfunction can be modified to impose either hard or soft constraints onthe design. Hard constraints guarantee compliance by the design. Softconstraints are used by the GA to “nudge” designs toward desirableattributes, but do not entirely preclude outlier designs.

-   -   1) Height and Width    -   2) Area (minimum and/or maximum—to comply with regulatory        standards)    -   3) Presence of retroreflective elements in certain areas (i.e.        to enforce presence of material on the shoulders for ANSI        standards compliance)    -   4) Apply a mask to the design, to define the region of vest        The chromosome with the lowest fitness is replaced with copies        of the chromosomes that have the highest fitness. See Steps C        and D in FIG. 13. This can be done in various ways. In some        embodiments, Single Tournament Selection is used with a        tournament size of 4. This approach requires random assignment        of each chromosome to a group of 4. The two inferior chromosomes        are replaced with copies of the two superior chromosomes in that        group. These copies may be exact replicas of the two superior        parents or each child may be created using some genetic material        from each parent. This later approach is called crossover (see        Step E in FIG. 13). The children are then mutated (see Step F in        FIG. 13). In the case of our proof-of-concept implementation,        mutation involves randomly perturbing one or more [x, y]        vertices in our chromosome.

Finally, determination is made as to whether the termination criterionhas been met (see Step G in FIG. 13). Termination of the algorithm canbe done after a predetermined number of generations.

The present disclosure also provides a system and method to exploitretroreflection for training of an object part detector. The term“object part detector” as used herein means a detector that can findindividual parts of an object in image/video instead of finding thewhole object itself.

Optical articles with retroreflective properties appear bright in imageswhere a light source is projected on them. Therefore, when images ofthese optical articles are intensity-thresholded, the object may appearas a connected component in the resulting binary image. In the presentdisclosure, this property is used to segment (if there are any) parts ofan optical article. The sequence of steps to perform this methodology isdescribed here and a sample workflow for a single instance of theoptical article is depicted in FIG. 14.

An input image is provided. The image is annotated with the bounding boxlocation of the entire object of interest (such as an optical article)(as shown in step (a) in FIG. 14). Note that the annotation does notinclude any information e.g. count or location of the parts of theobject. Intensity thresholding and morphological operations like closingwhich includes dilation and erosion are carried on the image. Theseprovide binary image (images if run for multiple thresholds) whereconnected components provide image patches. The set of image patches canbe separated into two sets—all image patches which do not have anyoverlap with the bounding box annotation and constitute the background(as shown in step (e) in FIG. 14). The other set includes patches withsome overlap with the ground truth annotation (as shown in step (d) inFIG. 14). The set of patches with overlap can be pruned by using asizing heuristic to eliminate noisy patches left behind as an artifactof morphology. The set of constituent parts can include a patternrepeated across the object (as shown an example in step (a) in FIG. 14)or different parts. These can be discovered by a clustering algorithmwhich can determine the number of parts of the object. The number ofconstituent parts may be provided through human supervision also.Finally, a detector model is trained for the discovered constituent partof the object (as shown in step (f) in FIG. 14). This model is trainedto detect a specific part of the object of interest in a scene.

In some embodiments, a potential method of characterization of thepresently disclosed optical articles having a plurality ofretroreflective elements includes a distribution function. For example,it might be characterized in terms of retro-reflective elements orfeatures (reflecting a given wavelength and/or polarization potentiallywith a particular intensity) with a certain distribution of sizes and acertain distribution of spacing and relative position of the componentelements. This type of characterization might be utilized to enableadditional capabilities such as object classification (e.g., onecharacterization associated with one class of object and anothercharacterization associate with a second class of object) or to enableproduct authentication. It could also be characterized by a distributiongenerated from a non-dimensional ratio determined from theconstellation. For example the size of a node divided by the distance tothe next closest node.

In the present disclosure, only a portion of the optical article that issufficient to accurately sample the distribution is required forcategorization. For example if an optical article contains manyelements, X, that are part of the constellation, only a small number ofvisible elements, n, may be required for a statistically significantsample of the population (i.e. n<<X.) This will improve the robustnessof the categorization when the view of the article is partially occludedor distorted.

The presented disclosure also provides a system and method to exploitretroreflection for part based detection. The system combines twoproperties of optical articles, particularly with retroreflectiveproperties: under certain morphological operations on an intensitythresholded image of an optical article, the resulting connectedcomponents is likely to include the whole object that certain opticalarticles are composed of constituent parts or may be modified to be acomposition of repeating parts and some of these parts would be visiblewhen the optical article is partially visible in its pose or occluded byother objects.

These two properties can be used by running a monolithic detector tosearch for the complete object of interest (such as infrastructure, agarment, an accessory, or other objects on which the presently disclosedoptical article is disposed) and combining it with a detector that looksfor its constituent part(s). The sequence of steps to perform thismethodology is depicted in FIG. 15 and described here:

The input to the system is an image of a scene where an object ofinterest (such as infrastructure, a garment, an accessory, or otherobjects on which the presently disclosed optical article is disposed)may be present along with detector models that are trained to find thewhole optical article disposed on the object of interest and separately,its constituent parts. The optical article on the object may becompletely visible or partially visible due to pose or occlusion. Imagepatches which can include the optical article are generated in two ways:by intensity thresholding that help segment the constituent parts (asshown in step (b) FIG. 15) or thresholding combined with morphologicaloperations (as shown in step (c) in FIG. 15).

The part(s) detector is run on the first pool of candidates as they aretrained to look for the smaller compositional parts of the opticalarticle (as shown in step (d) in FIG. 15) while the whole objectdetector is run on the image patches extracted after morphologicaloperations (as shown in step (e) in FIG. 15). Finally, the output ofrunning the two different detector frameworks is combined (as shown instep (f) in FIG. 15). Even if the entire optical article may not bedetected by the monolithic detector, the part based detector willdiscover some of the optical article thereby indicating presence of thearticle in the scene.

FIG. 16 also offers a process scheme for training and testing a systemfor observing disclosed articles. The top half of FIG. 16 describes thetraining of the system. In some embodiments, + (positive data) and −(negative data) are fed into the training. The training could go oversome iterations based on the training problem formulation. The lowerhalf of FIG. 16 describes the testing stage when the test set is fedinto the trained algorithm and an evaluation is carried out. If thetesting stage determines that the figure of merit for identification hasnot been met, additional training (e.g., via the method depicted in thetop half of FIG. 16) can be undertaken.

The input (Training Images or Test Images) can be a plurality of images,wherein each image includes a specific garment configuration in areal-world or synthetic setting. Obtaining the positive dataset caninclude collecting real world and/or synthetic images/videos of thedesign on the object of interest (e.g. safety vest under differentposes, viewpoint, distance, illumination and occlusion conditions).Obtaining the negative dataset can include collecting images/videos ofother objects found in the application environment. Input data (+/−)contains images of an individual wearing a certain design (e.g. standardH design) present in some environment (e.g. near a road). The parts ofthe image containing the garment represents (+ve) data and all otherregions represent (−ve) data. A human or a pre-trained computer (e.g.heuristic guided) labeler marks the regions (with the assistance of ahuman expert) that contain the garment (+ve data) in these images. Basedon these markings, the computer extracts the positive and the negativedata from the images.

All this data (Training set) is then utilized to train an algorithmwhose goal is to learn to distinguish between the positive and negativedata points (image regions). The trained algorithm is then evaluatedagainst an independent test set.

The lower left block in FIG. 16 illustrates an independently collectedtest dataset (e.g., test images) of positive and negative images/videosof the application environment. The test set may be collected in thesame manner as the training set. The computational algorithm can be aclassifier algorithm trained for an object of interest using thetraining dataset. For each garment configuration, a computationalalgorithm can be developed based on the set of training images for thegarment configuration. This can be followed by a set of test images forsaid garment configuration running through the computational algorithmdeveloped from the input of training images of said garmentconfiguration. The actual labels marked by human on the garments arekept hidden (BLIND STUDY) from the algorithm and may be used as abenchmark for evaluating its performance. Area under curve (AUC) orother measures can be utilized for a quantitative evaluation.

The output from such a system can be obtained by applying the classifieron test dataset(s) and computing metrics for evaluation e.g.classification accuracy, false positive rate, precision, recall, AUC.The final output includes evaluation metrics for evaluating the efficacyof said garment configuration. The output may include classificationaccuracy, false positive rate, specificity and sensitivity.

While one particular implementation of a computing system is describedherein, other configurations and embodiments of computing systemsconsistent with and within the scope of the present disclosure will beapparent to one of skill in the art upon reading the present disclosure.Various modifications and alterations of the present disclosure willbecome apparent to those skilled in the art without departing from thescope and spirit of this invention.

EXAMPLES

Objects and advantages may be further illustrated by the followingexamples, but the particular materials and amounts thereof recited inthese examples, as well as other conditions and details, should not beconstrued to unduly limit this disclosure.

Materials

3M™ SCOTCHLITE™ Reflective Material 8906 Silver Fabric Trim (3M Company,St Paul, Minn.)—referred to in the examples as “silver fabric trim”.

3M™ SCOTCHLITE™ Reflective Material C750 Silver Transfer Film (3MCompany, St Paul, Minn.)—referred to in the examples as “silver transferfilm”.

3M™ SCOTCHLITE™ Reflective Material C790 Carbon Black Stretch TransferFilm (3M Company, St Paul, Minn.)—referred to in the examples as “blacktransfer film”.

3M™ SCOTCHLITE™ Reflective Material 8710 Silver Transfer Film (3MCompany, St Paul, Minn.)—referred to herein as “silver transfer film 2”.

3M™ SCOTCHLITE™ Reflective Material 8986 Fluorescent Red-Orange FlameResistant Fabric (3M Company, St Paul, Minn.)—referred to herein as“orange fabric”.

3M™ SCOTCHLITE™ Reflective Material 8987 Fluorescent Lime-Yellow FlameResistant Fabric (3M Company, St Paul, Minn.)—referred to herein as“yellow fabric”.

A commercially available vest named “High-visibility Class 2 vest”,style #100501 made by Carhartt (Dearborn, Mich.) is an example of a ‘H’pattern—referred to in the examples as “H pattern vest” or “H patterngarment”.

Transmission Measurements

Optical transmission spectra in both the visible and near-infraredwavelength ranges were measured using an optical spectrophotometer(UltrascanPro from Hunter Associates Laboratory Reston, Va.)

Coefficient of Retroreflectivity

Retroreflectivity was measured using the test criteria described in AS™E810-03 (2013) —Standard Test Method for Coefficient of RetroreflectiveSheeting (R_(A)) using the Coplanar Geometry at 0.2₀ observation angleand 5₀ entrance angle, i.e. 0.2/5₀ angle. Retroreflective units arereported in cd/lux/m₂.

The angle retroreflectivity measurement followed ANSI/ISEA 107-2010standard.

Example 1 Non-Quantitative Human Observation

Daytime visual inspection by human observers was utilized to determinethat the combination of retroreflective elements in FIG. 17a was moreconspicuous than either of the combinations seen in FIG. 17b or 17 c.

Example 2 Detectability of Garment Using a Machine Vision System

The following camera systems were utilized. The visible light colorcamera system was a FLIR Machine Vision (formerly Point Grey)CHAMELEON®3 5MP Color Camera (CM3-U3-50S5C-CS) (FLIR Integrated ImagingSolutions Inc., Richmond BC, CANADA) with an Edmund Optics 25 mm CSeries Fixed Focal Length Lens (Edmund Optics Inc. Barrington, N.J.).The near infrared monochrome camera system was a FLIR Machine Vision(formerly Point Grey) CHAMELEON®3 5MP Color Camera (CM3-U3-50S5C-CS)(FLIR Integrated Imaging Solutions Inc., Richmond BC, CANADA) with anEdmund Optics 25 mm C Series Fixed Focal Length Lens (Edmund Optics Inc.Barrington, N.J.) and a BN940 Narrow Near-IR Bandpass Filter(BN940-25.5) (Midwest Optical Systems, Inc. Palatine, Ill.). A 130 mmOver Drive Ring Light 940 nm IR—“EZ Mount Ring Light” from Smart VisionLights (Muskegon, Mich.) was synched to the NIR camera and served as thelight source for the NIR Monochrome Camera system. The light source forthe visible light color camera system was either ambient illumination orautomobile headlights.

Four illustrative garments were made. Comparative Example 2a was alime-yellow background vest with a H pattern made thereon with silverfabric trim as seen in FIG. 18a . Comparative Example 2b was the vest ofComparative Example 2a with 25.4 mm squares of silver transfer filmaffixed adjacent to H pattern with 12.7 mm gap from the H patternmaterial silver fabric trim as seen in FIG. 18b . Example 2c was thevest of Comparative Example 2a with 25.4 mm squares of black transferfilm 1 affixed adjacent to H pattern with 12.7 mm gap from the H patternsilver fabric trim as seen in FIG. 18c . Example 2d was the vest ofComparative Example 2a with 25.4 mm squares of both silver transfer filmand black transfer film alternating affixed adjacent to H pattern with12.7 mm gap from the H pattern material silver fabric trim as seen inFIG. 18d . In the examples shown in FIGS. 18a-18d , the square sizeswere 25.4 mm and the gaps from H pattern to squares were 17.2 mm with asquare to square gap of 31.75 mm and silver and black squaresalternating. The dimension used in these example are based on hardwareconsiderations and ability to detect and analyze features at a preferredobservation distance. Other dimensions and configurations are possible.

Images of an individual wearing the high-visibility garments ofComparative Examples 2a and 2b and Examples 2c and 2d were taken underdaytime ambient illumination conditions at various distances (e.g., 50,100, 150 feet) with a visible light color camera system (RGB) and anear-infrared monochrome camera system (NIR). The sample images capturedusing a visible light color camera system (RGB) at 100 feet are shown inFIGS. 18a, 18b, 18c and 18 d.

The images of the garments were segmented into various components(fluorescent background material, silver H pattern component, silversquares, and/or black squares). The maximum, minimum, and median pixelvalue from the various components was calculated. Table 1 shows thisdata normalized separately for the NIR and RGB images on a 0-1 scale(with 1 being fully saturated).

TABLE 1 Pixel intensity from daylight images from Inventive andComparative Examples NIR NIR NIR RGB RGB RGB Material High Low MedianHigh Low Median Fluorescent Lime-Yellow 0.80 0.39 0.41 0.99 0.23 0.56Background Silver Reflective H 1.00 0.36 0.62 1.00 0.11 0.20 Silverreflective square 0.91 0.49 0.75 0.82 0.20 0.21 Black reflective square0.60 0.31 0.47 0.19 0.06 0.08

The pixel intensities from the various examples under outdoor daylightconditions show a wide range in intensity due to material type,orientation, shadowing, etc. The RGB pixel intensity range for the blacksquares did not overlap with the pixel intensity range for that of thefluorescent background whereas the pixel intensity range for the silversquares and silver H components did overlap with the pixel intensityrange for that of the fluorescent background. Therefore, under certaindaylighting conditions, regions of the garment containing silverreflective have intensities that are not distinguishable from thebackground intensity, thereby limiting the ability to utilize thereflective elements for object detection. The garment having the blacksquares showed less overlap in terms of a range of pixel intensitycompared to range of pixel intensity for the background material whenimaged using an RGB camera system versus a garment having silversquares. Under similar illumination conditions, the black reflectiveexhibits superior contrast and provides a more robust contrast withrespect to the background material.

Example 3

Example 3a (E3a) was prepared by applying 0.025 m squares black transferfilm 1 and laminating them to a H pattern vest with the H-pattern trimsilver fabric trim sewn thereon. The squares were positioned 0.013 mfrom the silver fabric trim on both sides in an alternating pattern andspaced with 0.032 m between the squares. Lamination of the silvertransfer film was done using a transfer press such as that commerciallyavailable under the trade designation “Stahls' Hotronix Thermal TransferPress STX20” from Stahls' Hotronix, Carmichaels, Pa. at 130 C (265 F)for a dwell time of 20 seconds at an airline pressure setting of 3-4.

Example 3b (E3b) was prepared by applying 0.025 m squares silvertransfer film and black transfer film 1 and laminating them to a Hpattern vest with the H-pattern trim silver fabric trim sewn thereon.The squares were positioned 0.013 m from the silver fabric trim on bothsides in an alternating pattern and spaced with 0.032 m between thesquares. Lamination of the silver transfer film and the black transferfilm 1 was done using a transfer press such as that commerciallyavailable under the trade designation “Stahls' Hotronix Thermal TransferPress STX20” from Stahls' Hotronix, Carmichaels, Pa. at 177 C (350 F)for a dwell time of 15 seconds at an airline pressure setting of 3-4.

Comparative Example 1 (CE3c) is a commercially available vest named“High-visibility Class 2 vest”, style #100501 made by Carhartt,Dearborn, Mich., using 3M Scotchlite 8906 Silver Fabric Trim sewn ontolime yellow cotton polyester mesh vest.

Comparative Example 2 (CE3d) was prepared by applying 0.025 m squares ofsilver transfer film and laminating them to a H pattern vest with theH-pattern trim silver fabric trim sewn thereon. The squares werepositioned 0.013 m from the silver fabric trim on both sides in analternating pattern and spaced with 0.032 m between the squares.Lamination of the silver transfer film was done using a transfer presssuch as that commercially available under the trade designation “Stahls'Hotronix Thermal Transfer Press STX20” from Stahls' Hotronix,Carmichaels, Pa. at 177 C (350 F) for a dwell time of 20 seconds at anairline pressure setting of 3-4.

Comparative Example 3 (CE3e) was prepared by applying 0.025 m squares ofsilver transfer film and laminating them to a H pattern vest with theH-pattern trim silver fabric trim sewn thereon. The squares of Scotch2510 Black Masking Tape/Ruban/Cinta and the squares of silver transferfilm were positioned on the H pattern vest (laminated for the silvertransfer film and adhered for the black masking tape) in an alternatingpattern (i.e. silver-colored retroreflective material followed by blacktape squares) and spaced 0.032 m in between squares.

FIG. 38 shows an image of the vest of Example 3b (top panel) and CE3e(bottom panel) captured with the NIR system described above. As seen bycomparing the two panels, the retroreflective properties provided by theblack retroreflective film versus the black tape provide additionalsignal and additional occlusion resistance if some of the squares areblocked by the wearer or other obstructions.

Example 4 BRDF Measurements of Optical Contrasts using Bright CoverageDetermination

Two replicate photopic BRDFs (bi-directional reflectance distributionfunctions) were measured for each sample with and θ=0°, 16°, 30°, 45°,60° and 75° and ϕ=90° with a Radiant Imaging IS-SA Imaging Sphere(Radiant Vision Systems formerly Radiant Imaging, Redmond, Wash., USA).The photopic BRDF corresponds to the CIE-Y BRDF measured with thisinstrument. This instrument gives CIE-Y values for illuminant E.

The analyses were conducted under a variety of different illuminationconditions that represent real-life scenarios for daytime illumination.The analysis was focused on the CIE-Y BRDFs, as the Y factor representsrelative luminance or a level of relative brightness. The CIE-Y BRDFswere exported using the IS-SA instrument software into Cartesiancoordinates in θ_(X)-θ_(Y) space with increment and resolution for theexported data set to 1°. Note that the instrumental resolution is about1.5°. The θ_(X)-θ_(Y) angle space is defined as

θ_(X)=θ*sin(ϕ) θ_(Y)=θ*cos(ϕ)

The BRDFs were converted into u_(X)-u_(Y) space and then thresholded inthe region in u_(X)-u_(Y) space where u<sin(70°) and u_(Y)<sin(θ—15°)with threshold values of 0.05, 0.10 and 0.15 inverse steradians. Thethreshold values were chosen based on applications with typicalbackground fabrics used in high-visibility safety garment applicationsas referenced in standards such as ANSI/ISEA-107 (2015) and EN ISO20471. For example, a typical fluorescent lime-yellow fabric used inhigh-visibility garments can be approximated as a Lambertian reflectorwith a CIE-Y BRDF of about 0.18 inverse steradians. A typicalfluorescent orange fabric used in high-visibility garments can beapproximated as a Lambertian reflector with a CIE-Y BRDF of about 0.10inverse steradians. Therefore, 0.05, 0.10 and 0.15 inverse steradiansare reasonable CIE-Y BRDF cutoff values.

The thresholded BRDF images were used to calculate the bright coveragefor the respective retroreflective materials. Tables 2 to 4 give thebright coverage values averaged over the two replicated measurements.The weighted average bright coverage percent was obtained by weightingthe bright coverage using a weighting factor proportional to cosine oftheta. The weighting factors were normalized so that their sum is equalto unity. The weighted-averaged bright coverage gives a metric thatsamples a broad range of illumination and viewing geometries that canoccur as mentioned earlier.

TABLE 2 Bright coverage (%) for BRDF cutoff = 0.05 inverse steradianIncidence Angles (degrees) Weighted Sample ID 0 16 30 45 60 75 AverageBlack transfer 3.5 9.1 4.9 9.3 8.1 11.2 7.0 film Orange fabric 100.0100.0 100.0 100.0 100.0 100.0 100.0 Silver fabric film 50.1 84.0 77.251.1 41.0 33.2 61.2

TABLE 3 Bright coverage (%) for BRDF cutoff = 0.10 inverse steradianIncidence Angles (degrees) Weighted Sample ID 0 16 30 45 60 75 AverageBlack transfer 0.0 0.0 0.0 2.2 3.4 4.2 1.0 film Orange fabric 100.0100.0 100.0 100.0 100.0 100.0 100.0 Silver fabric film 16.8 49.2 46.428.5 17.7 12.9 31.8

TABLE 4 Bright coverage (%) for BRDF cutoff = 0.15 inverse steradianIncidence Angles (degrees) Weighted Sample ID 0 16 30 45 60 75 AverageBlack transfer film 0.0 0.0 0.0 0.0 1.9 2.3 0.4 Orange fabric 2.5 7.719.9 25.8 44.7 32.0 17.7 Silver fabric film 6.5 35.5 29.5 19.9 11.9 8.020.5

The results show that the black reflector gives the lowest brightcoverage which is desirable when using with typical background materialsused with high-visibility garments. The other reflectors give muchhigher bright coverage values. The lower bright coverage from the blacktransfer film provides a significantly higher contrast, and thereforebetter detection under a wider variety of illumination conditions,compared to a typical silver material by itself.

Example 5 Observation of Angular Sensitivity

Example 5a (E5a) was prepared by cutting 0.025 m squares of 3MScotchlite 8725 Silver Transfer Film, 3M Scotchlite 8965 White Fabricand SRI part #: RC-C725-30.0CM-8001-CP4 and laminating or adhering themto cotton woven fabric. Squares were positioned in a grid with 0.05 mspaces between squares in the X and Y directions and positioned in aparallel pattern to create vertical columns across the grid. Laminationof the 3M Scotchlite 8725 Silver Transfer Film and SRI part #:RC-C725-30.0CM-8001-CP4 was done using a transfer press such as thatcommercially available under the trade designation “Stahls' HotronixThermal Transfer Press STX20” from Stahls' Hotronix, Carmichaels, Pa. at177 C (350 F) for a dwell time of 20 seconds at an airline pressuresetting of 4. Adhesion of the 3M Scotchlite 8965 White Fabric was doneusing Scotch™ Essentials Wardrobe Tape available from 3M Company of StPaul, Minn. See FIG. 19.

Example 5b (E5b) was prepared by cutting 0.025 m squares of 3MScotchlite 8725 Silver Transfer Film, 3M Scotchlite 8965 White Fabricand SRI part #: RC-C725-30.0CM-8001-CP4 and laminating or adhering themto cotton woven fabric. Squares were positioned in a grid with 0.05 mspaces between squares in the X and Y directions in an ABC alternatingpattern to create diagonal rows across the grid. Lamination of the 3MScotchlite 8725 Silver Transfer Film and SRI part #:RC-C725-30.0CM-8001-CP4 was done using a transfer press such as thatcommercially available under the trade designation “Stahls' HotronixThermal Transfer Press STX20” from Stahls' Hotronix, Carmichaels, Pa. at177 C (350 F) for a dwell time of 20 seconds at an airline pressuresetting of 4. Adhesion of the 3M Scotchlite 8965 White Fabric was doneusing Scotch™ Essentials Wardrobe Tape available from 3M Company of StPaul, Minn. See FIG. 20.

Example 5c (E5c) was prepared in columns as in Example 1, but thesquares were spaced 0.075 m apart. See FIG. 21.

Example 5e (E5e) was prepared in columns as in Example 1, but thesquares were spaced 0.1 m apart. See FIG. 23.

Example 5f (E5f) was prepared in diagonal rows as in Example 2, but thesquares were spaced 0.1 m apart. See FIG. 24.

Example 5g (E5g) was prepared by cutting 0.013 m squares of 3MScotchlite 8725 Silver Transfer Film, 3M Scotchlite 8965 White Fabricand SRI part #: RC-C725-30.0CM-8001-CP4 and laminating or adhering themto cotton woven fabric. Squares were positioned in a grid with 0.025 mspaces between squares in the X and Y directions and positioned in aparallel pattern to create vertical columns across the grid. Laminationof the 3M Scotchlite 8725 Silver Transfer Film and SRI part #:RC-C725-30.0CM-8001-CP4 was done using a transfer press such as thatcommercially available under the trade designation “Stahls' HotronixThermal Transfer Press STX20” from Stahls' Hotronix, Carmichaels, Pa. at177 C (350 F) for a dwell time of 20 seconds at an airline pressuresetting of 4. Adhesion of the 3M Scotchlite 8965 White Fabric was doneusing Scotch™ Essentials Wardrobe Tape available from 3M Company of StPaul, Minn. See FIG. 25.

Example 5h (E5h) was prepared by cutting 0.013 m squares of 3MScotchlite 8725 Silver Transfer Film, 3M Scotchlite 8965 White Fabricand SRI part #: RC-C725-30.0CM-8001-CP4 and laminating or adhering themto cotton woven fabric. Squares were positioned in a grid with 0.025 mspaces between squares in the X and Y directions in an ABC alternatingpattern to create diagonal rows across the grid. Lamination of the 3MScotchlite 8725 Silver Transfer Film and SRI part #:RC-C725-30.0CM-8001-CP4 was done using a transfer press such as thatcommercially available under the trade designation “Stahls' HotronixThermal Transfer Press STX20” from Stahls' Hotronix, Carmichaels, Pa. at177 C (350 F) for a dwell time of 20 seconds at an airline pressuresetting of 4. Adhesion of the 3M Scotchlite 8965 White Fabric was doneusing Scotch™ Essentials Wardrobe Tape available from 3M Company of StPaul, Minn. See FIG. 26.

Example 5i (E5i) was prepared in columns as in Example 7, but thesquares were spaced 0.038 m apart. See FIG. 27.

Example 5j (E5j) was prepared in diagonal rows as in Example 8, but thesquares were spaced 0.038 m apart. See FIG. 28.

Example 5k (E5k) was prepared in columns as in Example 7, but thesquares were spaced 0.05 m apart. See FIG. 29.

Example 5l (E5l) was prepared in diagonal rows as in Example 8, but thesquares were spaced 0.05 m apart. See FIG. 30.

Comparative Example 5 m (C5 m) was prepared by cutting 0.025 m squaresof 3M Scotchlite 8725 Silver Transfer Film and laminating them to wovencotton fabric. Squares were positioned in a grid with 0.05 m spacesbetween squares in the X and Y directions. Lamination was done using atransfer press such as that commercially available under the tradedesignation “Stahls' Hotronix Thermal Transfer Press STX20” from Stahls'Hotronix, Carmichaels, Pa. at 177 C (350 F) for a dwell time of 20seconds at an airline pressure setting of 4. See FIG. 31.

Comparative Example 5n (C5n) was prepared by cutting 0.025 m squares of3M Scotchlite 8965 White Fabric and adhering them to woven cottonfabric. Squares were positioned in a grid with 0.05 m spaces betweensquares in the X and Y directions. Adhesion was done using Scotch™Essentials Wardrobe Tape available from 3M Company of St Paul, Minn. SeeFIG. 32.

Comparative Example 5o (C5o) was prepared by cutting a 0.1 m square of3M Scotchlite 8725 Silver Transfer Film and laminating to woven cottonfabric. Lamination was done using a transfer press such as thatcommercially available under the trade designation “Stahls' HotronixThermal Transfer Press STX20” from Stahls' Hotronix, Carmichaels, Pa. at177 C (350 F) for a dwell time of 20 seconds at an airline pressuresetting of 4. See FIG. 33.

This test was performed using the low beam headlights of a 2015 ToyotaHighlander XLE driving at a speed of approx. 15 mph. with a Nikon D700016.2 megapixel Digital SLR camera with a Nikon 105 mm Lens (Nikon,Tokyo, JAPAN), attached to a tripod and placed above the middle consoleand in line with the driver's head. Two (2) observers were sitting inthe back of the car and one driver was gathering appearance data alongwith the photo and video recorded with the camera. Examples 5a-5l weremounted on foam 1.2×2.4 m core or tube 0.22 m diameter and were testedwith at least one of Comparative Examples 5m to 5o. The samples wererotated +/−approximately 90 angle around the vertical and then thehorizontal axes. The car stopped every 76 m between 610 m and 3 m toevaluate samples by notation and photo documentation.

Table 5 describes samples and appearance at different viewing distances.Legend: S—Silver, B—Black, W—White, C—Column, D—Diagonal, So—Solid,M—monochromatic.

TABLE 5 distance distance distance first flickering shapes shape sizevisible observed observed Example (m) spacing material pattern (m) (m)(m) E5a 0.025 × 0.025 2x S/B/W C 533 381 244 E5b 0.025 × 0.025 2x S/B/WD >152 >152 >152 E5c 0.025 × 0.025 3x S/B/W C >152 >152 >152 E5e 0.025 ×0.025 4x S/B/W C 381 305 244 E5f 0.025 × 0.025 4x S/B/W D >152 >152 >152E5g 0.013 × 0.013 2x S/B/W C >152 >152 >76 E5h 0.013 × 0.013 2x S/B/WD >152 >176 >76 E5i 0.013 × 0.013 3x S/B/W C >152 >152 >152 E5j 0.013 ×0.013 3x S/B/W D >152 >152 >152 E5k 0.013 × 0.013 4x S/B/WC >152 >152 >152 E5l 0.013 × 0.013 4x S/B/W D >152 >152 >152 C5m 0.025 ×0.025 2x S M 533 N/A 183 C5n 0.025 × 0.025 2x W M 381 N/A 244 C5o 0.1 ×0.1 0x S So >152 N/A N/A

Table 6 indicates head on brightness showing all reflecting and 2 offangles demonstrating how the retro reflectivity changes with the viewingangle of different materials. Because of the different off-angleretro-reflective properties of the materials, as shown in Table 6,different angles create different appearances. At head on angles, whereall materials reflect well, the full array is seen while at anglesfurther to the side from head on (off angles) materials with lowoff-angle retro reflectivity do not reflect much therefore these rows orcolumns tend to disappear. Table 6 shows the very low off-anglereflectivity of the SRI part #: RC-C725-30.0CM-8001-CP4.

TABLE 6 Black Silver White candelas/ candelas/ candelas/ Angle (lux *meter²) (lux * meter²) (lux * meter²)  0.2, 5 (Head-on) 393 514 104 0.2, 40 9 324 39 0.33, 30 43 348 57

FIGS. 34 and 35 shows head on and FIGS. 36 and 37 shows these rowsvirtually disappearing at off angles. FIG. 34 shows an image of panelsoriented close to ‘head-on’ entrance angle orientation for modified ‘yawangle’ experiment. Distance from panel to source/camera wasapproximately 152 m. FIG. 35 shows a magnified image of the test panelfrom FIG. 34 identifying the 0.025×0.025 m retroreflective elements.Under this orientation (surface normal of the panel approximatelyparallel with the illumination source/detector light), all of theretroreflective elements are visible. FIG. 36 shows an image of the testpanel oriented at a ‘yaw angle’ orientation of approximately 30 degreeswith respect to the viewing direction. Under these conditions, thesilver retroreflective elements are still visible, but the blackretroreflective elements are significantly less visible. FIG. 37 shows amagnified image of the test panel from FIG. 36 identifying the0.025×0.025 m retroreflective elements. Under these conditions, thesilver retroreflective elements are still visible, but the blackretroreflective elements are significantly less visible.

The on/off blinking occurred with these grid patterns. With ringpatterns such as bullseye, the overglow of the brighter materials causesthe brighter materials to appear to grow and shrink (or pulse) as theadjacent materials become more dim. Other dynamically varying effectscreated by arranging the shapes could include vanishing effect,growing/enlarging effect, other optical illusions of movement, etc.

Embodiments

Disclosed herein are optical articles comprising a spatially definedarrangement of a plurality of data rich retroreflective elements,wherein the plurality of retroreflective elements compriseretroreflective elements having at least two different retroreflectiveproperties and at least two different optical contrasts with respect toa background substrate when observed within an ultraviolet spectrum, avisible spectrum, a near-infrared spectrum, or a combination thereof.

Also disclosed are articles according to previous embodiments, whereinthe retroreflective elements have at least two different opticalcontrasts in the near-infrared region with respect to the backgroundsubstrate. Also disclosed are articles according to any of the previousembodiments, wherein the difference in optical contrast is described bya bright coverage of 0.05 with weighted average bright coverage of lessthan 50 percent. Also disclosed are articles according to any of theprevious embodiments, wherein the difference in optical contrast has a0.05 bright coverage with weighted average bright coverage of less than25 percent. Also disclosed are articles according to any of the previousembodiments, wherein the difference in optical contrast has a 0.05bright coverage with weighted average bright coverage of less than 15percent. Also disclosed are articles according to any of the previousembodiments, wherein the difference in optical contrast has a 0.10bright coverage with weighted average bright coverage of less than 25percent. Also disclosed are articles according to any of the previousembodiments, wherein the difference in optical contrast has a 0.10bright coverage with weighted average bright coverage of less than 20percent. Also disclosed are articles according to any of the previousembodiments, wherein the difference in optical contrast has a 0.10bright coverage with weighted average bright coverage of less than 15percent. Also disclosed are articles according to any of the previousembodiments, wherein the difference in optical contrast has a 0.15bright coverage with weighted average bright coverage of less than 15percent. Also disclosed are articles according to any of the previousembodiments, wherein the retroreflectivity coefficient of theretroreflective elements at an observation angle/entrance angle 0.2°/5°is greater than 50 cd/lux-m2, greater than 100 cd/lux-m2, or greaterthan 200 cd/lux-m2. Also disclosed are articles according to any of theprevious embodiments, the optical article comprises high visibilitysafety apparel. Also disclosed are articles according to any of theprevious embodiments, wherein the data rich plurality of retroreflectiveelements are configured in a repeating spatially defined arrangementsuch that the information is interpretable even when the portion of theretroreflective elements are occluded. Also disclosed are articlesaccording to any of the previous embodiments, wherein the opticalarticle is a deformable optical article. Also disclosed are articlesaccording to any of the previous embodiments, wherein the deformation isat least one of a shrinkage or an expansion. Also disclosed are articlesaccording to any of the previous embodiments, wherein the deformationcauses a spacing change between at least two of the retroreflectiveelements. Also disclosed are articles according to any of the previousembodiments, wherein the deformation is reversible. Also disclosed arearticles according to any of the previous embodiments, wherein at leasttwo different retroreflective properties are at least two differentretroreflective intensity values. Also disclosed are articles accordingto any of the previous embodiments, wherein at least two differentretroreflective properties are at least two different retroreflectiveintensity values when viewed at different viewing angles. Also disclosedare articles according to any of the previous embodiments, theretroreflective property changes in response to a change in condition.Also disclosed are articles according to any of the previousembodiments, wherein the change in condition is at least one of a changein thermal, moisture, mechanical deformation, or radiation. Alsodisclosed are articles according to any of the previous embodiments,wherein the retroreflective elements are individually sized andseparated from one another such that each individual retroreflectiveelement is resolvable at desired distances from the optical article.Also disclosed are articles according to any of the previousembodiments, wherein the spatially defined arrangement comprisesgeometric arrangement in which the retroreflective elements arepositioned with a distance from their neighboring retroreflectiveelements, and wherein the retroreflective elements have a periodicityfrom one element to another within the spatially defined arrangement.Also disclosed are articles according to any of the previousembodiments, wherein the periodicity is a regular periodicity. Alsodisclosed are articles according to any of the previous embodiments, theperiodicity is an irregular periodicity. Also disclosed are articlesaccording to any of the previous embodiments, wherein the spatiallydefined arrangement is rotationally insensitive. Also disclosed arearticles according to any of the previous embodiments, wherein a numberof geometric arrangements required per spatially defined arrangementdepends on a required quality of fit. Also disclosed are articlesaccording to any of the previous embodiments, wherein theretroreflective elements are positioned from their nearest neighboringretroreflective elements by a characteristic distance. Also disclosedare articles according to any of the previous embodiments, wherein theretroreflective elements have a characteristic ratio of size to distanceto neighboring retroreflective elements that is invariant with viewingangle. Also disclosed are articles according to any of the previousembodiments further comprising a printed layer disposed on the outersurface of at least a portion of the retroreflective elements. Alsodisclosed are articles according to any of the previous embodiments,wherein the retroreflective properties are detectable in the infraredspectrum. Also disclosed are articles according to any of the previousembodiments, wherein the at least two retroreflective elements arediscontinuous. Also disclosed are articles according to any of theprevious embodiments, wherein the plurality of retroreflective elementsare discontinuous. Also disclosed are articles according to any of theprevious embodiments, wherein the optical article is disposed on asubstrate selected from at least one of infrastructure, wearables, andvehicles.

Also disclosed are fabrics comprising the article according to any ofthe previous embodiments.

Also disclosed are systems that comprise a) an article according to anyof the previous embodiments; b) an optical system; and c) an inferenceengine for interpreting and classifying the plurality of retroreflectiveelements wherein the optical system feeds data to the inference engine.

Also disclosed are systems according to any of the previous embodiments,wherein the article is disposed on at least one of infrastructure,targets, wearables, and vehicles. Also disclosed are systems accordingto any of the previous embodiments, the optical system is part of avehicle, and further wherein the vehicle uses the information as aninput to an autonomous driving module. Also disclosed are systemsaccording to any of the previous embodiments, wherein the vehicle usesthe information to provide human language feedback to the driver. Alsodisclosed are systems according to any of the previous embodiments,wherein the vehicle uses the information to provide at least one ofhaptic, audible or visual feedback to the driver. Also disclosed aresystems according to any of the previous embodiments, the data richplurality of retroreflective elements is visible in the infraredspectrum. Also disclosed are systems according to any of the previousembodiments, the information related to the data rich plurality ofretroreflective articles comprises at least one of road workersexpected, pedestrians expected, construction workers expected, studentsexpected, emergency responder workers expected. Also disclosed aresystems according to any of the previous embodiments, wherein theinference engine is locally stored as a component of the optical system.Also disclosed are systems according to any of the previous embodiments,the optical system communicates with the inference engine using awireless communication protocol.

Thus, embodiments of optical articles and systems interacting with thesame are disclosed. The implementations described above and otherimplementations are within the scope of the following claims. Oneskilled in the art will appreciate that the present disclosure can bepracticed with embodiments other than those disclosed. The disclosedembodiments are presented for purposes of illustration and notlimitation.

1. An optical article comprising a spatially defined arrangement of aplurality of data rich retroreflective elements, wherein the pluralityof retroreflective elements comprise retroreflective elements having atleast two different retroreflective properties and at least twodifferent optical contrasts with respect to a background substrate whenobserved within an ultraviolet spectrum, a visible spectrum, anear-infrared spectrum, or a combination thereof.
 2. The articleaccording to claim 1, wherein the retroreflective elements have at leasttwo different optical contrasts in the near-infrared region with respectto the background substrate, and wherein the difference in opticalcontrast is described by a bright coverage of 0.05 with weighted averagebright coverage of less than 50 percent.
 3. (canceled)
 4. The articleaccording to claim 2, wherein the difference in optical contrast has a0.05 bright coverage with weighted average bright coverage of less than25 percent.
 5. The article according to claim 2, wherein the differencein optical contrast has a 0.05 bright coverage with weighted averagebright coverage of less than 15 percent.
 6. The article according toclaim 2, wherein the difference in optical contrast has a 0.10 brightcoverage with weighted average bright coverage of less than 25 percent.7. The article according to claim 2, wherein the difference in opticalcontrast has a 0.10 bright coverage with weighted average brightcoverage of less than 20 percent.
 8. The article according to claim 2,wherein the difference in optical contrast has a 0.10 bright coveragewith weighted average bright coverage of less than 15 percent.
 9. Thearticle according to claim 2, wherein the difference in optical contrasthas a 0.15 bright coverage with weighted average bright coverage of lessthan 15 percent.
 10. The article according to claim 1, wherein theretroreflectivity coefficient of the retroreflective elements at anobservation angle/entrance angle 0.2°/5° is greater than 50 cd/lux-m2,greater than 100 cd/lux-m2, or greater than 200 cd/lux-m2.
 11. Thearticle according to claim 1, wherein the optical article comprises highvisibility safety apparel.
 12. (canceled)
 13. The article according toclaim 1, wherein the optical article is a deformable optical article.14. The article of claim 1, wherein the deformation is at least one of ashrinkage or an expansion, and wherein the deformation causes a spacingchange between at least two of the retroreflective elements, and furtherwherein the deformation is reversible.
 15. (canceled)
 16. (canceled) 17.(canceled)
 18. (canceled)
 19. The article according to claim 1, whereinthe retroreflective property changes in response to a change incondition.
 20. The article according to claim 19 wherein the change incondition is at least one of a change in thermal, moisture, mechanicaldeformation, or radiation.
 21. (canceled)
 22. The article according toclaim 1, wherein the spatially defined arrangement comprises geometricarrangement in which the retroreflective elements are positioned with adistance from their neighboring retroreflective elements, and whereinthe retroreflective elements have a periodicity from one element toanother within the spatially defined arrangement.
 23. The articleaccording to claim 22, wherein the periodicity is a regular periodicity.24. The article according to claim 22, wherein the periodicity is anirregular periodicity.
 25. The article according to claim 1, wherein thespatially defined arrangement is rotationally insensitive.
 26. Thearticle according to claim 25, wherein a number of geometricarrangements required per spatially defined arrangement depends on arequired quality of fit.
 27. The article according to claim 25, whereinthe retroreflective elements are positioned from their nearestneighboring retroreflective elements by a characteristic distance.28-43. (canceled)